There is a nonvolatile memory device in which a resistance change unit and an ion supply unit are provided between two electrodes.
In such a nonvolatile memory device, when a voltage is applied using the electrode on the ion supply unit side as a positive pole and the electrode on the resistance change unit side as a negative pole, a metal included in the ion supply unit is ionized to diffuse into the resistance change unit and receives electrons from the electrode on the negative pole side. Thereby, a conduction path (filament) of a metal is formed between the two electrodes. This leads to a situation where the resistance between the electrode on the ion supply unit side and the electrode on the resistance change unit side is low.
On the other hand, when a voltage of the opposite polarity is applied, the metal forming the conduction path is ionized, and thereby the conduction path becomes short and furthermore disappears. This leads to a situation where the resistance between the electrode on the ion supply unit side and the electrode on the resistance change unit side is high.
Thus, at least two resistance states can be created, and data can therefore be stored.
However, in such a nonvolatile memory device, for example, there is a problem that the formed conduction path becomes short or something to change the resistance state even in a state where no voltage is applied.
Hence, it is desired to develop a nonvolatile memory device in which the properties that resistance states can be retained for a long time (data retention properties) are high.